Technical Field
The present invention relates to a liquid jet head and a liquid jet apparatus.
Related Art
Conventionally, ink jet-type liquid jet heads have been used to eject ink droplets onto recording paper or the like to record texts and graphics or eject a liquid material onto the surface of an element substrate to forma functional thin film.
In the ink-jet type, a liquid such as an ink or a liquid material is guided from a liquid tank through a supply tube into a channel (ejection grooves), and a pressure is applied to the liquid charged in the channel to eject the liquid from a nozzle communicating with the channel. Then, at the time of ejecting the liquid, texts and graphics are recorded or a functional thin film of a determined shape is formed while the liquid jet head or the recording medium is moved.
The kinds of liquid jet heads include an edge shoot-type liquid jet head (hereinafter, called simply “edge shoot-type head”) and a side shoot-type liquid jet head (hereinafter, called simply “side shoot-type head”), for example.
The edge shoot-type head is structured to have nozzle holes at the end of an ink flow path such that the ink is ejected from the nozzle holes. In the thus configured edge shoot-type head, when air bubbles exist in the ink, the air bubbles may be accumulated in the nozzle holes to interfere with ejection of the ink.
Meanwhile, the side shoot-type head is structured to eject the ink from nozzle holes in the middle of an ink flow path. In the thus structured side shoot-type head, the nozzle holes are provided in the middle of the ink flow path, and therefore air bubbles are unlikely to be retained in the nozzle holes and their surroundings as compared to the edge shoot-type head.
Accordingly, as a particularly preferred edge shoot-type liquid jet head, JP 2015-77737 A discloses a vertical circulation-type liquid jet head (hereinafter, called “vertical circulation-type head”).
The vertical circulation-type head includes a nozzle plate with nozzle holes, an actuator plate, ejection grooves provided in one side surface of the actuator plate into which the ink flows, a return path provided in the other side surface of the actuator plate, a circulation channel that has a side flow path communicating with the ejection grooves, the return path, and the nozzle holes.
In the vertical circulation-type head, the distance between the ejection grooves and the return path is shorter than that in the side flow path of the side shoot-type head, and the width of the side flow path is narrow in the direction from the ejection grooves to the return path.
Accordingly, the ink flowing in the circulation channel descends along the ejection grooves, and then turns back immediately and rises in the return path. Therefore, when the flow velocity of the ink is low, the ink may be less easy to flow. That is, air bubbles are hard to be removed from the side flow path and may be retained in the side flow path between the nozzle holes and the ejection grooves.
In the case of using the vertical circulation-type head, the air bubbles in the nozzle holes may move to the side flow path and remain in the side flow path.
Further, the entire side flow path needs to be formed on the actuator plate, thereby complicating the manufacturing process for the actuator plate.
The present invention is devised in light of the foregoing circumstances. An object of the present invention is to provide a liquid jet head and a liquid jet apparatus that can suppress retention of air bubbles in a side flow path positioned between nozzle holes and ejection grooves to suppress accumulation of the air bubbles in the nozzle holes, and can simplify the manufacturing process.